From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92E39C433FE for ; Tue, 8 Mar 2022 18:02:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241039AbiCHSDp (ORCPT ); Tue, 8 Mar 2022 13:03:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35788 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234429AbiCHSDk (ORCPT ); Tue, 8 Mar 2022 13:03:40 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 24AF724F2B; Tue, 8 Mar 2022 10:02:43 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E7FFE1516; Tue, 8 Mar 2022 10:02:42 -0800 (PST) Received: from wubuntu (unknown [10.57.71.199]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C8AB03FA45; Tue, 8 Mar 2022 10:02:41 -0800 (PST) Date: Tue, 8 Mar 2022 18:02:40 +0000 From: Qais Yousef To: linux-kernel@vger.kernel.org Cc: linux-tip-commits@vger.kernel.org, Abhijeet Dharmapurikar , Valentin Schneider , "Peter Zijlstra (Intel)" , "Steven Rostedt (Google)" , x86@kernel.org, stable@vger.kernel.org Subject: Re: [tip: sched/core] sched/tracing: Don't re-read p->state when emitting sched_switch event Message-ID: <20220308180240.qivyjdn4e3te3urm@wubuntu> References: <20220120162520.570782-2-valentin.schneider@arm.com> <164614827941.16921.4995078681021904041.tip-bot2@tip-bot2> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <164614827941.16921.4995078681021904041.tip-bot2@tip-bot2> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org +CC stable On 03/01/22 15:24, tip-bot2 for Valentin Schneider wrote: > The following commit has been merged into the sched/core branch of tip: > > Commit-ID: fa2c3254d7cfff5f7a916ab928a562d1165f17bb > Gitweb: https://git.kernel.org/tip/fa2c3254d7cfff5f7a916ab928a562d1165f17bb > Author: Valentin Schneider > AuthorDate: Thu, 20 Jan 2022 16:25:19 > Committer: Peter Zijlstra > CommitterDate: Tue, 01 Mar 2022 16:18:39 +01:00 > > sched/tracing: Don't re-read p->state when emitting sched_switch event > > As of commit > > c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu") > > the following sequence becomes possible: > > p->__state = TASK_INTERRUPTIBLE; > __schedule() > deactivate_task(p); > ttwu() > READ !p->on_rq > p->__state=TASK_WAKING > trace_sched_switch() > __trace_sched_switch_state() > task_state_index() > return 0; > > TASK_WAKING isn't in TASK_REPORT, so the task appears as TASK_RUNNING in > the trace event. > > Prevent this by pushing the value read from __schedule() down the trace > event. > > Reported-by: Abhijeet Dharmapurikar > Signed-off-by: Valentin Schneider > Signed-off-by: Peter Zijlstra (Intel) > Reviewed-by: Steven Rostedt (Google) > Link: https://lore.kernel.org/r/20220120162520.570782-2-valentin.schneider@arm.com Any objection to picking this for stable? I'm interested in this one for some Android users but prefer if it can be taken by stable rather than backport it individually. I think it makes sense to pick the next one in the series too. Thanks! -- Qais Yousef